U.S. patent number 11,096,202 [Application Number 16/611,473] was granted by the patent office on 2021-08-17 for method for d2d operation of terminal in wireless communication system and terminal using said method.
This patent grant is currently assigned to LG Electronics Inc.. The grantee listed for this patent is LG ELECTRONICS INC.. Invention is credited to Hyunho Lee, Seungmin Lee.
United States Patent |
11,096,202 |
Lee , et al. |
August 17, 2021 |
Method for D2D operation of terminal in wireless communication
system and terminal using said method
Abstract
The present invention provides a method for carrying out
S-TTI-based communication performed by a terminal supporting a
relatively short transmission time interval (S-TTI) compared to a
legacy transmission time interval (L-TTI) in a wireless
communication system. The method is characterized by: determining a
value with respect to a ratio of reference signal energy per
resource element (RS EPRE) to physical downlink shared channel
energy per resource element (PDSCH EPRE); and carrying out
S-TTI-based communication on the basis of the value with respect to
the ratio, wherein the value with respect to the ratio is
determined in an S-TTI unit.
Inventors: |
Lee; Seungmin (Seoul,
KR), Lee; Hyunho (Seoul, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
LG ELECTRONICS INC. |
Seoul |
N/A |
KR |
|
|
Assignee: |
LG Electronics Inc. (Seoul,
KR)
|
Family
ID: |
1000005743286 |
Appl.
No.: |
16/611,473 |
Filed: |
May 8, 2018 |
PCT
Filed: |
May 08, 2018 |
PCT No.: |
PCT/KR2018/005247 |
371(c)(1),(2),(4) Date: |
November 06, 2019 |
PCT
Pub. No.: |
WO2018/208054 |
PCT
Pub. Date: |
November 15, 2018 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20200170031 A1 |
May 28, 2020 |
|
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
62505891 |
May 13, 2017 |
|
|
|
|
62502610 |
May 6, 2017 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W
72/1257 (20130101); H04W 72/1273 (20130101); H04L
5/0044 (20130101); H04L 5/0007 (20130101); H04W
92/18 (20130101) |
Current International
Class: |
H04L
5/00 (20060101); H04W 72/12 (20090101); H04W
92/18 (20090101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
105850177 |
|
Aug 2016 |
|
CN |
|
20170022826 |
|
Mar 2017 |
|
KR |
|
2016117984 |
|
Jul 2016 |
|
WO |
|
2017053637 |
|
Mar 2017 |
|
WO |
|
2017074520 |
|
May 2017 |
|
WO |
|
Other References
PCT International Application No. PCT/KR2018/005247, International
Searching Authority dated Aug. 16, 2018, 5 pages. cited by
applicant .
LG Electronics, "Discussion on dynamic switching between 1ms TTI
and sTTI," 3GPP TSG-RAN WG1 #88, R1-1702419, Feb. 2017, 5 pages.
cited by applicant .
Ericsson, "WF L1 configurations for multicast in FeMTC," 3GPP
TSG-RAN WG1 #88, R1-1703516, Feb. 2017, 6 pages. cited by applicant
.
Qualcomm, "Email discussion [90-10] on sTTI CSI Reporting," 3GPP
TSG-RAN WG1 #90b, R1-1718119, Oct. 2017, 21 pages. cited by
applicant .
European Patent Office Application Serial No. 18798534.6, Search
Report dated Mar. 19, 2020, 9 pages. cited by applicant .
ITRI, "Discussion on CSI reporting for sTTI operation", 3GPP TSG
RAN WG1 Meeting #88bis, R1-1705537, Apr. 2017, 2 pages. cited by
applicant.
|
Primary Examiner: Skripnikov; Alex
Assistant Examiner: Chowdhury; Sharmin
Attorney, Agent or Firm: Lee Hong Degerman Kang Waimey
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is the National Stage filing under 35 U.S.C. 371
of International Application No. PCT/KR2018/005247, filed on May 8,
2018, which claims the benefit of U.S. Provisional Application No.
62/502,610, filed on May 6, 2017, and 62/505,891, filed on May 13,
2017, the contents of which are all hereby incorporated by
reference herein in their entireties.
Claims
What is claimed is:
1. A method for S-TTI-based communication performed by a terminal
supporting a short transmission time interval (S-TTI) that is
relatively shorter compared to a legacy transmission time interval
(L-TTI) in a wireless communication system, comprising: determining
a value with respect to a ratio of a reference signal energy per
resource element (RS EPRE) to a physical downlink shared channel
(PDSCH) energy (PDSCH energy per resource element (PDSCH EPRE));
performing the S-TTI based communication based on the value with
respect to the ratio, and determining the value with respect to the
ratio in the S-TTI unit; and determining whether one S-TTI based
physical downlink control channel (S-PDCCH) schedules an S-TTI
based PDSCH (S-PDSCH) on a plurality of S-TTIs, wherein when the
one S-PDCCH schedules the S-PDSCH on the plurality of S-TTIs, the
value with respect to the ratio is equally applied to the plurality
of S-TTIs.
2. The method of claim 1, further comprising: determining whether
RS is received in a specific S-TTI among a plurality of S-TTIs.
3. The method of claim 2, wherein when the RS is not received in
the specific S-TTI, a value with respect to a ratio related to
transmission power of a downlink channel on the specific S-TTI is
additionally signaled.
4. The method of claim 3, wherein the downlink channel includes the
S-PDSCH or the S-PDCCH.
5. The method of claim 2, wherein when the RS is not received in
the specific S-TTI, a value with respect to a ratio related to
transmission power of a downlink channel on the specific S-TTI is
set to follow a value with respect to a ratio applied to the S-TTI
to which the RS is transmitted among the plurality of S-TTIs.
6. The method of claim 2, wherein when the RS is not received in
the specific S-TTI, as a value with respect to a ratio related to
transmission power of a downlink channel on the specific S-TTI, a
sum of a value with respect to a ratio applied to the S-TTI to
which the RS is transmitted among the plurality of S-TTIs and a
preset offset value is applied.
7. The method of claim 1, wherein when the S-TTI to which the RS is
transmitted among the plurality of S-TTIs, a value with respect to
a ratio for the S-TTI to which the RS is transmitted is applied to
the plurality of S-TTIs.
8. The method of claim 1, wherein when the one S-PDCCH schedules
the S-PDSCH on the plurality of S-TTIs, a value with respect to a
ratio is signaled in units of the plurality of S-TTIs.
9. The method of claim 1, wherein when the one S-PDCCH schedules
the S-PDSCH on the plurality of S-TTIs, an average value of values
with respect to a ratio related to the plurality of S-TTIs is
applied to the plurality of S-TTIs.
10. The method of claim 1, wherein when the one S-PDCCH schedules
the S-PDSCH on the plurality of S-TTIs, a value with respect to a
ratio related to a preset S-TTI among the plurality of S-TTIs is
applied to the plurality of S-TTIs.
11. A terminal supporting a short transmission time interval
(S-TTI) that is relatively shorter compared to a legacy
transmission time interval (L-TTI) in a wireless communication
system, comprising: a radio frequency (RF) transceiver configured
to transmit and receive a radio signal; and a processor configured
to be operated in combination with the RF transceiver, wherein the
processor: determines a value with respect to a ratio of a
reference signal energy per resource element (RS EPRE) to a
physical downlink shared channel (PDSCH) energy (PDSCH energy per
resource element (PDSCH EPRE)), performs the S-TTI based
communication based on the value with respect to the ratio and
determines the value with respect to the ratio in the S-TTI unit,
and determines whether one S-TTI based physical downlink control
channel (S-PDCCH) schedules an S-TTI based PDSCH (S-PDSCH) on a
plurality of S-TTIs, wherein when the one S-PDCCH schedules the
S-PDSCH on the plurality of S-TTIs, the value with respect to the
ratio is equally applied to the plurality of S-TTIs.
Description
BACKGROUND
Field
The present document relates to wireless communication, and more
particularly, to a method for a D2D operation of a terminal in a
wireless communication system and a terminal using the method.
Related Art
In the International Telecommunication Union Radio Communication
Sector (ITU-R), standardization of International Mobile
Telecommunication (IMT)-Advanced, a next generation mobile
communication system after 3rd generation, is underway.
IMT-Advanced aims to support IP (Internet Protocol) based
multimedia service at data rates of 1 Gbps in a stationary and
low-speed moving state and 100 Mbps in a high-speed moving
state.
The 3rd Generation Partnership Project (3GPP) is a system standard
that meets the requirements of IMT-Advanced, and LTE-Advanced
(LTE-A), which has improved Long Term Evolution (LTE) based on
Orthogonal Frequency Division Multiple Access (OFDMA)/Single
Carrier-LTE-Advanced (LTE-A), is being prepared. LTE-A is one of
the strong candidates for IMT-Advanced.
Recently, the interest in device-to-device (D2D) technology for
direct communication between devices is increasing. In particular,
the D2D is drawing attention as a communication technology for a
public safety network. Commercial communication networks are
rapidly changing to LTE, but current public safety networks are
mainly based on 2G technology in terms of conflict and cost with
the existing communication standards. The technical gap and the
need for improved services are leading to efforts to improve the
public safety networks.
In the present document, when a terminal (or base station) performs
S-TTI-based wireless communication, there is a need to provide a
configuration for supporting the S-TII-based wireless
communication.
SUMMARY
The present document provides a method for a D2D operation of a
terminal in a wireless communication system and a terminal using
the method.
In an aspect, a method for S-TTI-based communication performed by a
terminal supporting a short transmission time interval (S-TTI) that
is relatively shorter compared to a legacy transmission time
interval (L-TTI) in a wireless communication system is provided.
The method may comprise determining a value with respect to a ratio
of a reference signal energy per resource element (RS EPRE) to a
physical downlink shared channel (PDSCH) energy (PDSCH energy per
resource element (PDSCH EPRE)) and performing the S-TTI based
communication based on the value with respect to the ratio, and
determining the value with respect to the ratio in the S-TTI
unit.
The method may further comprise determining whether RS is received
in a specific S-TTI among a plurality of S-TTIs.
When the RS is not received in the specific S-TTI, a value with
respect to a ratio related to transmission power of a downlink
channel on the specific S-TTI may be additionally signaled.
The downlink channel may include an S-TTI based PDSCH (S-PDSCH) or
an S-TTI based physical downlink control channel (S-PDCCH).
When the RS is not received in the specific S-TTI, a value with
respect to a ratio related to transmission power of a downlink
channel on the specific S-TTI may be set to follow a value with
respect to a ratio applied to the S-TTI to which the RS is
transmitted among the plurality of S-TTIs.
When the RS is not received in the specific S-TTI, as a value with
respect to a ratio related to transmission power of a downlink
channel on the specific S-TTI, a sum of a value with respect to a
ratio applied to the S-TTI to which the RS may be transmitted among
the plurality of S-TTIs and a preset offset value is applied.
The method may further comprise determining whether one S-TTI based
physical downlink control channel (S-PDCCH) schedules an S-TTI
based PDSCH (S-PDSCH) on a plurality of S-TTIs.
When the one S-PDCCH schedules the S-PDSCH on the plurality of
S-TTIs, the value with respect to the ratio may be equally applied
to the plurality of S-TTIs.
When the S-TTI to which the RS is transmitted among the plurality
of S-TTIs, a value with respect to a ratio for the S-TTI to which
the RS may be transmitted is applied to the plurality of
S-TTIs.
When the one S-PDCCH schedules the S-PDSCH on the plurality of
S-TTIs, a value with respect to a ratio may be signaled in units of
the plurality of S-TTIs.
When the one S-PDCCH schedules the S-PDSCH on the plurality of
S-TTIs, an average value of values with respect to a ratio related
to the plurality of S-TTIs may be applied to the plurality of
S-TTIs.
When the one S-PDCCH schedules the S-PDSCH on the plurality of
S-TTIs, a value with respect to a ratio related to a preset S-TTI
among the plurality of S-TTIs may be applied to the plurality of
S-TTIs.
In another aspect, a method for S-TTI-based communication performed
by a terminal supporting a short transmission time interval (S-TTI)
that is relatively shorter compared to a legacy transmission time
interval (L-TTI) in a wireless communication system is provided.
The method may comprise determining a value with respect to a ratio
of a reference signal energy per resource element (RS EPRE) to a
physical downlink shared channel (PDSCH) energy (PDSCH energy per
resource element (PDSCH EPRE)) and performing the S-TTI based
communication based on the value with respect to the ratio, and
determining the value with respect to the ratio for each restricted
CSI measurement set when restricted channel state information (CSI)
measurement is signaled for each S-TTI set.
A value for a ratio of a symbol in which RS is received may be set
differently for each of the restricted CSI measurement sets, and a
value with respect to a ratio of a symbol in which the RS is not
received may be equally for all restricted CSI measurement
sets.
In other aspects, a terminal supporting a short transmission time
interval (S-TTI) that is relatively shorter compared to a legacy
transmission time interval (L-TTI) in a wireless communication
system is provided. The method may comprise a radio frequency (RF)
transceiver configured to transmit and receive a radio signal and a
processor configured to be operated in combination with the RF
transceiver, wherein the processor determines a value with respect
to a ratio of a reference signal energy per resource element (RS
EPRE) to a physical downlink shared channel (PDSCH) energy (PDSCH
energy per resource element (PDSCH EPRE)), and performs the S-TTI
based communication based on the value with respect to the ratio
and performs the value with respect to the ratio in the S-TTI
unit.
According to the present document, the ratio of the RS EPRE to the
PDSCH EPRE may be determined in the S-TTI unit.
In addition, according to the present document, if there is no RS
on the particular S-TTI, the method for determining a ratio of RS
energy to PDSCH energy may also be provided.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a wireless communication system.
FIG. 2 is a diagram showing a wireless protocol architecture for a
user plane.
FIG. 3 is a diagram showing a wireless protocol architecture for a
control plane.
FIG. 4 illustrates a system structure of a new generation radio
access network (NG-RAN) to which the NR is applied.
FIG. 5 illustrates a functional division between the NG-RAN and the
5GC.
FIG. 6 schematically illustrates an example of S-TTI and L-TTI.
FIG. 7 schematically illustrates another example of the S-TTI and
the L-TTI.
FIG. 8 schematically illustrates another example of the S-TTI and
the L-TTI.
FIG. 9 schematically illustrates an example in which a serving cell
is subjected to interference from a neighboring cell.
FIG. 10 is a flowchart of a method for carrying out S-TTI based
communication according to an embodiment of the present
document.
FIG. 11 is a flowchart of a method for carrying out S-TTI based
communication according to another embodiment of the present
document.
FIG. 12 is a block diagram illustrating a communication device in
which the embodiment of the present document is implemented.
FIG. 13 is a block diagram illustrating an example of devices
included in a processor.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
Hereinafter, terms or abbreviations that are not separately defined
may be defined in 3GPP TS 36 series or TS 38 series.
FIG. 1 illustrates a wireless communication system. This may also
be called an evolved-UMTS terrestrial radio access network
(E-UTRAN), or a long term evolution (LTE)/LTE-A system.
The E-UTRAN includes at least one base station (BS) 20 which
provides a control plane and a user plane to a user equipment (UE)
10. The UE 10 may be fixed or mobile, and may be referred to as
another terminology, such as a mobile station (MS), a user terminal
(UT), a subscriber station (SS), a mobile terminal (MT), a wireless
device, etc. The BS 20 is generally a fixed station that
communicates with the UE 10 and may be referred to as another
terminology, such as an evolved node-B (eNB), a base transceiver
system (BTS), an access point, etc.
The BSs 20 are interconnected by means of an X2 interface. The BSs
20 are also connected by means of an S1 interface to an evolved
packet core (EPC) 30, more specifically, to a mobility management
entity (MME) through S1-MME and to a serving gateway (S-GW) through
S1-U.
The EPC 30 includes an MME, an S-GW, and a packet data
network-gateway (P-GW). The MME has access information of the UE or
capability information of the UE, and such information is generally
used for mobility management of the UE. The S-GW is a gateway
having an E-UTRAN as an end point. The P-GW is a gateway having a
PDN as an end point.
Layers of a radio interface protocol between the UE and the network
can be classified into a first layer (L1), a second layer (L2), and
a third layer (L3) based on the lower three layers of the open
system interconnection (OSI) model that is well-known in the
communication system. Among them, a physical (PHY) layer belonging
to the first layer provides an information transfer service by
using a physical channel, and a radio resource control (RRC) layer
belonging to the third layer serves to control a radio resource
between the UE and the network. For this, the RRC layer exchanges
an RRC message between the UE and the BS.
FIG. 2 is a diagram showing a wireless protocol architecture for a
user plane. FIG. 3 is a diagram showing a wireless protocol
architecture for a control plane. The user plane is a protocol
stack for user data transmission. The control plane is a protocol
stack for control signal transmission.
Referring to FIGS. 2 and 3, a PHY layer provides an upper layer
with an information transfer service through a physical channel.
The PHY layer is connected to a medium access control (MAC) layer
which is an upper layer of the PHY layer through a transport
channel Data is transferred between the MAC layer and the PHY layer
through the transport channel. The transport channel is classified
according to how and with what characteristics data is transferred
through a radio interface.
Data is moved between different PHY layers, that is, the PHY layers
of a transmitter and a receiver, through a physical channel. The
physical channel may be modulated according to an Orthogonal
Frequency Division Multiplexing (OFDM) scheme, and use the time and
frequency as radio resources.
The functions of the MAC layer include mapping between a logical
channel and a transport channel and multiplexing and demultiplexing
to a transport block that is provided through a physical channel on
the transport channel of a MAC Service Data Unit (SDU) that belongs
to a logical channel. The MAC layer provides service to a Radio
Link Control (RLC) layer through the logical channel.
The functions of the RLC layer include the concatenation,
segmentation, and reassembly of an RLC SDU. In order to guarantee
various types of Quality of Service (QoS) required by a Radio
Bearer (RB), the RLC layer provides three types of operation mode:
Transparent Mode (TM), Unacknowledged Mode (UM), and Acknowledged
Mode (AM). AM RLC provides error correction through an Automatic
Repeat Request (ARQ).
The RRC layer is defined only on the control plane. The RRC layer
is related to the configuration, reconfiguration, and release of
radio bearers, and is responsible for control of logical channels,
transport channels, and PHY channels. An RB means a logical route
that is provided by the first layer (PHY layer) and the second
layers (MAC layer, the RLC layer, and the PDCP layer) in order to
transfer data between UE and a network.
The function of a Packet Data Convergence Protocol (PDCP) layer on
the user plane includes the transfer of user data and header
compression and ciphering. The function of the PDCP layer on the
user plane further includes the transfer and encryption/integrity
protection of control plane data.
What an RB is configured means a procedure of defining the
characteristics of a wireless protocol layer and channels in order
to provide specific service and configuring each detailed parameter
and operating method. An RB can be divided into two types of a
Signaling RB (SRB) and a Data RB (DRB). The SRB is used as a
passage through which an RRC message is transmitted on the control
plane, and the DRB is used as a passage through which user data is
transmitted on the user plane.
If RRC connection is established between the RRC layer of UE and
the RRC layer of an E-UTRAN, the UE is in the RRC connected state.
If not, the UE is in the RRC idle state.
A downlink transport channel through which data is transmitted from
a network to UE includes a broadcast channel (BCH) through which
system information is transmitted and a downlink shared channel
(SCH) through which user traffic or control messages are
transmitted. Traffic or a control message for downlink multicast or
broadcast service may be transmitted through the downlink SCH, or
may be transmitted through an additional downlink multicast channel
(MCH). Meanwhile, an uplink transport channel through which data is
transmitted from UE to a network includes a random access channel
(RACH) through which an initial control message is transmitted and
an uplink shared channel (SCH) through which user traffic or
control messages are transmitted.
Logical channels that are placed over the transport channel and
that are mapped to the transport channel include a broadcast
control channel (BCCH), a paging control channel (PCCH), a common
control channel (CCCH), a multicast control channel (MCCH), and a
multicast traffic channel (MTCH).
The physical channel includes several OFDM symbols in the time
domain and several subcarriers in the frequency domain. One
subframe includes a plurality of OFDM symbols in the time domain.
An RB is a resources allocation unit, and includes a plurality of
OFDM symbols and a plurality of subcarriers. Furthermore, each
subframe may use specific subcarriers of specific OFDM symbols
(e.g., the first OFDM symbol) of the corresponding subframe for a
physical downlink control channel (PDCCH), that is, an L1/L2
control channel A Transmission Time Interval (TTI) is a unit time
for subframe transmission.
Hereinafter, a new radio access technology (new RAT) will be
described. The new radio access technology may be abbreviated as
new radio (NR).
As more communication devices require larger communication
capacities, there is a need for improved mobile broadband
communication compared to the existing radio access technology
(RAT). In addition, massive machine type communications (MTC),
which connects between multiple devices and objects to provide
various services anytime and anywhere, is also one of the major
issues to be considered in next-generation communication. In
addition, communication system designs considering
services/terminals that are sensitive to reliability and latency
have been discussed. The introduction of the next-generation
wireless access technologies in consideration of such enhanced
mobile broadband communication, the massive MTC, ultra-reliable and
low latency communication (URLLC), and the like, have been
discussed, and in the present document, for convenience, the
technology is referred to as new RAT or NR.
FIG. 4 illustrates a system structure of a new generation radio
access network (NG-RAN) to which the NR is applied.
Referring to FIG. 4, the NG-RAN may include gNB and/or eNB that
provides user plane and control plane protocol termination to a
terminal. FIG. 4 illustrates a case of including only the gNB. The
gNB and the eNB are connected to each other via an Xn interface.
The gNB and the eNB are connected to a 5G core network (5GC) via an
NG interface. More specifically, the gNB and the eNB are connected
to an access and mobility management function (AMF) via an the NG-C
interface, and are connected to a user plane function (UPF) via an
NG-U interface.
FIG. 5 illustrates a functional division between the NG-RAN and the
5GC.
Referring to FIG. 5, the gNB may provide functions such as
inter-cell radio resource management (inter cell RRM), radio bearer
management (RB control), connection mobility control, radio
admission control, and measurement configuration and provision, and
dynamic resource allocation. The AMF may provide functions such as
NAS security and idle state mobility processing. The UPF may
provide functions such as mobility anchoring and PDU processing.
The session management function (SMF) may provide functions such as
terminal IP address allocation and PDU session control.
FIG. 6 schematically illustrates an example of S-TTI and L-TTI.
Referring to FIG. 6, when the S-TTI is defined as a basic resource
unit that is preset (/signaled), the L-TTI may be interpreted in a
form in which preset (/signaled) K S-TTIs (basic resource units)
are combined.
FIG. 7 schematically illustrates another example of the S-TTI and
the L-TTI.
Referring to FIG. 7, when the L-TTI is defined as a basic resource
unit that is preset (/signaled), the S-TTI may be interpreted in a
form (for example, a kind of mini-basic resource units) in which
the L-TTI (basic resource unit) is divided into the (preset
(/signaled)) K number.
Unlike the example of the above drawing, the S-TTI may also have a
form in which a plurality of (preset (/signaled)) basic resource
units are combined.
FIG. 8 schematically illustrates another example of the S-TTI and
the L-TTI.
Referring to FIG. 8, for example, as in S-TTI configuration # A, a
first S-TTI may have a length of three OFDM symbols (OS), a second
S-TTI may have a length of two OFDM symbols, a third S-TTI may have
a length of two OFDM symbols, a fourth S-TTI may have a length of
two OFDM symbols, a fifth S-TTI may have a length of two OFDM
symbols, and a sixth S-TTI may have a length of three OFDM
symbols.
Alternatively, for example, as in S-TTI configuration # B, a first
S-TTI may have a length of seven OFDM symbols, and a second S-TTI
may also have a length of seven OFDM symbols.
So far, various examples of the relationship between the S-TTI and
the L-TTI have been shown. However, examples of various S-TTI and
L-TTI described above are merely examples for convenience of
description, and the forms of the S-TTI and L-TTI are not limited
to the forms disclosed above.
Hereinafter, the present document will be described.
As described above, in future wireless communication systems, S-TTI
based wireless communication systems are supported.
Accordingly, when a terminal performs wireless communication in a
specific cell, it may receive interference in an S-TTI unit (from a
neighboring cell providing S-TTI based wireless communication).
For convenience of understanding, an example in which a serving
cell receives interference in an S-TTI unit from a neighboring cell
and an example of interference in an L-TTI unit will be described
below with reference to the accompanying drawings.
FIG. 9 schematically illustrates an example in which a serving cell
is subjected to interference from a neighboring cell.
Referring to FIG. 9, there may be a neighboring cell A 910
providing S-TTI based wireless communication and a neighboring cell
B 930 providing L-TTI based wireless communication. In this case, a
serving cell 920, which is a cell in which a terminal performs a
wireless communication system, may be subjected to interference 921
by the neighboring cell A and/or interference 922 by the
neighboring cell B.
As can be seen in FIG. 9, the serving cell 920 may be subjected to
interference in the S-TTI unit by the neighboring cell A 910, and
may be subjected to interference in the L-TTI unit by the
neighboring cell B 930.
Conventionally, a ratio of RS energy to PDSCH energy (for example,
a ratio of a reference signal (RS) energy per resource element
(EPRE) to a physical downlink shared channel (PDSCH) EPRE) for
interference relaxation is determined in a subframe unit (that is,
L-TTI unit). However, as described above, upon performing the
S-TTI-based wireless communication in the neighboring cell, the
interference occurs in the S-TTI unit. To efficiently overcome the
interference, the present document is to provide a configuration
for determining the ratio of the RS (for example, CRS) EPRE to the
PDSCH EPRE.
For example, in the L-TTI (that is, legacy subframe), a
(cell-specific) RS (for example, CRS) is transmitted in every
subframe. However, when the L-TTI is divided into a plurality of
S-TTIs, the corresponding RS (for example, CRS) transmissions do
not exist on all the S-TTIs. Accordingly, the present document also
provides a method for determining a ratio of RS energy to PDSCH
energy in the case of the S-TTI in which there is no corresponding
RS (for example, CRS) transmission.
Also, as one example of the suggested methods below, a method for
efficiently carrying out a (S-TTI-based) channel/signal (for
example, S-PDCCH/PDSCH, S-PUCCH/PUSCH) transmission/reception
operation in consideration of different external interference
(pattern/level/amount) per S-TTI (SET) with different lengths when
S-TTI based communication is performed is suggested.
In the present document, the following abbreviations may be
defined. L-TTI: Refer to the operation based on the existing
(LEGACY) 1MS length (or the number of symbols greater than S-TTI).
In this case, L-TTI TX/RX: Refer to L-TTI-based channel/signal
transmission/reception. S-TTI: Refer to an operation based on the
number of symbols smaller than L-TTI. In this case, S-TTI TX/RX:
Refer to S-TTI-based channel/signal transmission/reception.
S-PDCCH/PDSCH, S-PUCCH/PUSCH: Refer to S-TTI based PDCCH/PDSCH and
PUCCH/PUSCH, respectively. L-PDCCH/PDSCH, L-PUCCH/PUSCH: Refer to
L-TTI-based PDCCH/PDSCH and PUCCH/PUSCH, respectively.
The matters assumed/considered in the present document are as
follows.
In a symbol in which preset (/signaled) reference signal (reference
signal (RS)) is transmitted, the "ratio of RS energy per resource
element (EPRE) to PDSCH EPRE" is named "RHO_A (for example,
UE-specific parameter)", and in a symbol in which the corresponding
RS is not transmitted, the "ratio of RS EPRE to PDSCH EPRE" is
named "RHO_B (for example, cell-specific parameter)".
Ex) The "reference signal" wording may be (restrictively)
interpreted as CRS (or CSI-RS or DM-RS).
Ex) The RHO_B may be derived (/calculated) as the "RHO_A" and the
"ratio of RHO_A to RHO_B" signaled from the network (or base
station).
FIG. 10 is a flowchart of a method for carrying out S-TTI based
communication according to an embodiment of the present
document.
Referring to FIG. 10, the terminal may determine a value with
respect to the ratio of the reference signal (RS) energy per
resource element (EPRE) to the physical downlink shared channel
(PDSCH) EPRE. Here, the value with respect to the ratio may be
determined in the S-TTI unit, and a specific example thereof will
be described later.
In this case, the terminal may be a terminal that supports a
relatively short transmission time interval compared (S-TTI) to a
legacy transmission time interval (L-TTI) in a wireless
communication system. At this time, the terminal may be a terminal
that supports not only the S-TTI but also the L-TTI.
Here, the terminal may determine whether the RS is received in a
specific S-TTI of a plurality of S-TTIs.
At this time, for example, when no RS is received in the specific
S-TTI, the value with respect to the ratio related to transmission
power of a downlink channel on the specific S-TTI may be
additionally signaled. Alternatively, for example, the downlink
channel may include an S-TTI based PDSCH (S-PDSCH) or an S-TTI
based physical downlink control channel (S-PDCCH).
At this time, for example, when no RS is received in the specific
S-TTI, the value with respect to the ratio related to the
transmission power of the downlink channel on the specific S-TTI
may be set to follow a value with respect to the ratio applied to
the S-TTI in which the RS is transmitted among the plurality of
S-TTIs. Alternatively, for example, when no RS is received in the
specific S-TTI, as the value with respect to the ratio related to
the transmission power of the downlink channel on the specific
S-TTI, the sum of the value with respect to the ratio applied to
the S-TTI in which the RS is transmitted among the plurality of
S-TTIs and the preset offset value may be applied.
Describing in detail the above contents, the following rules are as
follows.
(Rule # A) S-PDSCH (/S-PDCCH) TX POWER-related RHO_A (/RHO_B)
values on the S-TTI in which preset (/signaled) RSs are not
transmitted may be additionally set (/signaled).
Ex) The rule may be useful when the external interference amount
(the interference amount between S-TTI(s) of VICTIM cell may vary
depending on the presence or absence of CRS (/CSI-RS) TX of
AGRESSOR cell) is different for each S-TTI, (in particular) when
TM4-based S-PDSCH (/S-PDCCH) is transmitted.
(Rule #B) The RHO_A (/RHO_B) value related to S-PDSCH (/S-PDCCH) TX
POWER on the S-TTI to which the preset (/signaled) RS is not
transmitted is: (1) the RS may be set (/signaled) to follow the
RHO_A (/RHO_B) value applied to the transmitted S-TTI, or (2) the
sum of the preset (/signaled) offset value and the RHO_A (/RHO_B)
value applied to the S-TTI to which the corresponding RS is
transmitted may be applied.
Here, the terminal may determine whether one S-TTI based physical
downlink control channel (S-PDCCH) schedules S-TTI based PDSCHs on
a plurality of S-TTIs.
In this case, for example, when the one S-PDCCH schedules S-PDSCHs
on the plurality of S-TTIs, the value with respect to the ratio may
be equally applied to the plurality of S-TTIs. Alternatively, for
example, when there is an S-TTI in which the RS is transmitted
among the plurality of S-TTIs, the value with respect to the ratio
of the S-TTI in which the RS is transmitted may be applied on the
plurality of S-TTIs. Alternatively, for example, when the one
S-PDCCH schedules the S-PDSCHs on the plurality of S-TTIs, the
value with respect to the ratio may be signaled in units of the
plurality of S-TTIs. Alternatively, for example, when the one
S-PDCCH schedules the S-PDSCHs on the plurality of S-TTIs, an
average value of the values with respect to the ratio related to
the plurality of S-TTIs may be applied to the plurality of S-TTIs.
Alternatively, for example, when the one S-PDCCH schedules the
S-PDSCHs on the plurality of S-TTIs, the value with respect to the
ratio related to a preset S-TTI among the plurality of S-TTIs is
set to the plurality of S-TTIs.
Describing in detail the above contents, the following rules are as
follows.
(Rule #C) In a variable TTI environment, when one S-PDCCH schedules
the S-PDSCH on the plurality of S-TTI(s) with differently set
(/signaled) RHO_A (/RHO_B) values (for example, when one DCI
schedules multiple S-TTI PDSCHs), the RHO_A (/RHO_B) value can be
(finally) assumed according to the following rules.
Ex) When there is the S-TTI to which the RS (for example, CRS) is
transmitted among the multiple S-TTI(s) scheduled with one S-PDCCH,
the S-TTI related RHO_A (/RHO_B) to which the RS is transmitted may
be applied to the multiple S-TTI(s).
Ex) When there is the S-TTI in which the RS (for example, CRS) is
not transmitted among the multiple S-TTI(s) scheduled with one
S-PDCCH, the S-TTI related RHO_A (/RHO_B) in which the RS is not
transmitted can be applied to the multiple S-TTI(s). Here, as an
example, (at this time), if the S-TTI-related S-PDSCH power to
which the RS is not transmitted is set (/signaled) to a lower power
value compared to the S-TTI to which the RS is transmitted (for
example, when the CRS TX of the AGRESSOR cell is not performed and
thus the interference is assumed to be relatively low), the
performance of the S-PDSCH performance of the multiple S-TTI(s) may
be reduced.
Ex) In the case of the multiple S-TTI(s) scheduled with one
S-PDCCH, each RHO_A (/RHO_B) value (pre-set (/signaled)) may be
applied to each S-TTI.
Ex) Different RHO_A (/RHO_B) values may be signaled for each
VARIABLE TTI (length).
Ex) (Weighted) average value (or minimum (/maximum) value) of
multiple S-TTI(s) related RHO_A (/RHO_B) values (scheduled with one
S-PDCCH) is applied to the multiple S-TTI(s), or preset (/signaled)
Kth S-TTI-related RHO_A (/RHO_B) (to which RS is transmitted (or
not transmitted) (or on the time basis)) may be applied to the
multiple S-TTI(s).
Thereafter, the terminal may perform the S-TTI based communication
on the basis of the value with respect to the ratio (S1020). The
example in which the terminal performs the S-TTI based
communication is already described above, and therefore a detailed
description thereof will be omitted.
In addition, although not separately illustrated, the embodiment of
FIG. 10 may be combined (or separated) with the embodiments
described below (or described above). An example in which the
embodiment of FIG. 10 and the embodiment to be described later (or
described above) are combined will be omitted for convenience of
description.
As described above, when the terminal performs wireless
communication in a specific cell, the terminal may be subjected to
the interference in the S-TTI unit. Accordingly, when the terminal
performs restricted CSI measurement (per preset S-TTI set), a
discussion on how to determine the ratio of the reference signal
EPRE and the PDSCH EPRE (per different S-TTI set in which the
restricted CSI measurement is performed) is required.
FIG. 11 is a flowchart of a method for carrying out S-TTI based
communication according to another embodiment of the present
document.
Referring to FIG. 11, the terminal may determine the value with
respect to the ratio of the reference signal (RS) energy per
resource element (EPRE) to the physical downlink shared channel
(PDSCH) EPRE. Here, when the restricted channel state information
(CSI) measurement is signaled for each S-TTI set, the value with
respect to the ratio may be determined for each restricted CSI
measurement set, and a specific example thereof will be described
later.
In this case, the terminal may be a terminal that supports the
short transmission time interval (TTI) that is relatively shorter
compared to the legacy transmission time interval (L-TTI) in the
wireless communication system, and the terminal at this time may be
a terminal supporting not only the S-TTI but also the L-TTI.
Here, for example, the value with respect to the ratio of symbols
in which the RS is received may be set differently for each of the
restricted CSI measurement sets. Alternatively, for example, the
value with respect to the ratio of the symbol in which the RS is
not received may be set equally for all restricted CSI measurement
sets.
Describing in detail the above contents, the following rules are as
follows.
(Rule #D) When the restricted CSI measurement is set (/signaled)
for each S-TTI set (or pre-set (/signaled) time (/frequency)
resource unit set), RHO_A (/RHO_B) may be differently set
(/signaled) for each restricted CSI measurement set.
Ex) RHO_B (or RHO_A) values may be applied (/set (/signaled)) in
common between different restricted CSI measurement sets.
Ex) when the above rule is applied, the S-PDSCH (/S-PDCCH)
reception performance of the victim cell can be efficiently
guaranteed in consideration of different interference for each
restricted CSI measurement set.
Thereafter, the terminal may perform the S-TTI based communication
based on the value with respect to the ratio (S1120). The example
in which the terminal performs the S-TTI based communication is
already described above, and therefore a detailed description
thereof will be omitted.
In addition, although not separately illustrated, the embodiment of
FIG. 11 may be combined (or separated) with embodiments described
below (or described above). An example in which the embodiment of
FIG. 11 and the embodiment described later (or described above) are
combined will be omitted for convenience of description.
Hereinafter, additional embodiments will be described.
(Rule #E) When the existing (legacy) RS (for example, DM-RS) form
(/pattern) is split and allocated between S-TTIs (on the time
axis), consecutive antenna ports (for example, port 7/8) (in a CDM
form) may be mapped to adjacent (two) RS RE(s) on the frequency
axis. Here, for example, when the plurality of S-TTI(s) are
transmitted in a combined form, the existing antenna port mapping
(/RS form (/pattern)) (per RS RE) may be (equally) applied
(/assumed).
It is obvious that the examples of the suggested methods described
above may be included as one of the implementation methods of the
present document and therefore may also be regarded as a kind of
suggested schemes. In addition, the above-described suggested
methods may be independently implemented, but some suggested
methods may be implemented in combined (or merged) forms. For
example, the present document has described the suggested method
based on the 3GPP LTE system for convenience of description, but
the scope of the system to which the suggested method is applied
can be extended to other systems in addition to the 3GPP LTE
system. For example, the suggested methods of the present document
may be restrictively applied only when the S-TTI based
communication operation is set (/signaled).
FIG. 12 is a block diagram illustrating a communication device in
which the embodiment of the present document is implemented.
Referring to FIG. 12, a base station 100 includes a processor 110,
a memory 120, and a transceiver 130. The processor 110 implements
the suggested functions, processes and/or methods. The memory 120
is connected to the processor 110 and stores various information
for driving the processor 110. The transceiver 130 is connected to
the processor 110 and transmits and/or receives a radio signal.
The terminal 200 includes a processor 210, a memory 220, and an RF
unit 230. The processor 210 implements the suggested functions,
processes and/or methods. The memory 220 is connected to the
processor 210 and stores various information for driving the
processor 210. The transceiver 230 is connected to the processor
210 and transmits and/or receives a radio signal. The terminal 200
may perform a D2D operation to other terminals according to the
above-described method.
The processors 110 and 210 may include application-specific
integrated circuits (ASICs), other chipsets, a logic circuit, a
data processing device, and/or a converter that mutually converts a
baseband signal and a radio signal. The memories 120 and 220 may
include a read-only memory (ROM), a random access memory (RAM), a
flash memory, a memory card, a storage medium, and/or other storage
devices. The transceivers 130 and 230 may include one or more
antennas for transmitting and/or receiving radio signals. When the
embodiment is implemented in software, the above-described
technique may be implemented as modules (process, function, and the
like) for performing the above-described functions. The module may
be stored in the memories 120 and 220 and executed by the
processors 110 and 210. The memories 120 and 220 may be inside or
outside the processors 110 and 210, and may be connected to the
processors 110 and 210 by various well-known means.
FIG. 13 is a block diagram illustrating an example of devices
included in a processor.
Referring to FIG. 13, the processor may include a value determiner
1310 and a communication performer 1320 in terms of functionality.
Here, the processor may be the processor 210 of FIG. 12.
Here, the value determiner 1310 determines a value with respect to
a ratio of a reference signal (RS) energy per resource element
(EPRE) to a physical downlink shared channel (PDSCH) EPRE, but the
value with respect to the ratio may be determined in the S-TTI
unit. In addition, here, the communication performer 1320 may have
a function of performing the S-TTI based communication based on the
value with respect to the ratio.
The description of the device included in the above-described
processor is only one example, and the processor may further
include other functional elements or devices. In addition, specific
examples of operations performed by each of the functional devices
described above are as described above, and therefore the redundant
description thereof will be omitted.
* * * * *